The Thorny Oysters 



The Thorny-oyster Foot Shell {P. Spondyloideum, Gmel.) 

 has an outline somewhat suggesting the human foot. The animal 

 between these flat valves must be very thin. It was first de- 

 scribed as an oyster, and it long enjoyed a reputation for rarity. 

 It is found most abundantly in the Red Sea where it is partially 

 buried in coral reefs. G)lour, brownish red in indistinct con- 

 centric bands on a paler ground. Length, 3 inches. 



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